Brake



Jan. 6, 1942. R. A. GoEPFRlcH BRAKE Filed April 27, 1940 2 Sheets-Sheet l ATTORNEY.

Jan- 6 1942- R. A. GoEPFRlcH 2,269,262

BRAKE Fil'ed April 27, 1940 2 Sheets-Sheet 2 INVENTOR.

l /771 ma /7771 ATTORNEY.

Figura '1.

Patented Jai. s, 1942 UNITED STATE BRAKE Rudolph A. Goepirich, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend,

`Ind., a corporation of Delaware Applieauon April zr, im, semi Ne. 331,955

(ci. lss-152) 8 Claims.

This invention relates to brakes, and is illustrated as embodied in an internal expanding brake for an automobile wheel.

An object of the inventionA is to simplify a brake of a very effective type, by arranging a single hydraulic wheel-cylinder device to apply through mechanical connections balanced thrusts on the ends of two shoes whichv individually anchor at opposite ends during forward and rehydraulic cylinder I8 is provided with a pair of .fluid-summe pistons .|1, eeen or which is con- Figure l is a section through the brake, just l inside the head of the brake drum, showing the brake shoes in side elevation;

Figures 2 and 3 are partial sections on the lines2'2and$-3ofFigrel;

Flgure 4.is taken on the line 4-4 of Figure l and shows the brake applying parts of the mechanical or emergency brake;

Figure 5 shows a modication of 'the thrustapplying means of Figure 1:'

Figure s is a partial section on the une 6 6 of tacted at its outer, or brake-applying surface, by

a thrust link Il. Each of the thrust linksV I8 isconnected at its other (or outer) end to a iloating lever I9., The said levers I9 are, as will hereinafter be explained, the means for spreading the ends of the shoes to apply them to the drum when the wheel cylinder I6 is actuated.

The shoes Il and |2 each include a web portion 2o and a lining or friction portion 2|. 'It will be noted that the web of the shoe I2 is provided at each endvwith an extension 22 which projects upward beyond the adjacent anchor, and beyond the adjacent lower end of the web of the shoe Il. As shown more clearly in Figure 2, the web of the shoe l2 is beveled at 22 to clear the web of the shoe il and meet the lower` end of the lever 'I9 at 24.

The levers il, as well as the upper ends of the extensions 22 are positioned behind the web of the shoe Il, as indicated by the dotted lines of Figure 1. The levers l! have integral therewith arms 25 which are folded over the respective ends of theweb of shoe il to embrace the said web. 'Ihe inside surfaces oi' the bends or folds formed by the arms' 25 with their respective levers meet projections on the web of the shoe il, en-

gaging the said projections at 26. It will be seen,

Figure 'l is .a further modication of the thrust-applying means of Figures 1 and 5; and

Figure 8 is a section taken on the line 8-8 of The brake assembly shown as illustrative of my invention comprises generally 'a rotatable brake drum Il and brake shoes il and I2 adapted to at times irlctionally engagethe brake drum.' The brake shoes are shown positionedhorizontally,

i. e.,-so positioned that a line drawn from one end to the other of either of the shoes would be substantially horizontal. Y

A stationary backing plate -I3 is provided for receiving the braking torque and, for this pur.- pose, has xed thereto a pair of anchors Il and I5. A hydraulic wheel cylinder. Il, ftheconventional type, is secured to .the backing plate il and is preferably arranged generally centrally ommitetheuppershoell.

The structureof my improved brake is symmetrical.- and it 'will therefore be convenient to appropriate a single identifying number to each therefore, that the levers Il contact at 2l the respective ends of the shoe `I 2 and contact at 26 the respective ends of the shoe I l.

A notch 21 is cut in each of the thrust-transmitting levers I9 to receive end of the corresponding thrust link I8. Each of the levers also has a notch 2l below notch 21 for receiving one end of a connecting element 29 or 29a which is part of the mechanical or emergency brake applying linkage. The two velements fand 29a bear at the points 3l on the respective levers Il and extendvthrough openings ll in the backing plate. On theA side of the backing plate away from the shoes and brake drum the elements 2! and 29a are connected to a cable 32. Sliding movement of '29a along the cable 'is permitted, vwhile 2l is prevented from slipping of! the end of the cable by engagement with the enlarged end 3l of the cable. A spring, in compression between the elements 2l and 29a, serves to normally hold apart the ends of the said elements which are connected to the cable l2. -A conduit 3l encases the cable 32 and bears at its venll against .the element 22a. Movement of the cable leftward relaof two .similar of the brake assembly. Thebe tive-to the conduit causes the conduit, pressing against the element 29o, to compress the spring backing plate by bolts 44 (see Figure 2).

and tend to draw the ends of the elements'ZS and 29a together. lEach of the said elementsV then operates as a lever fulcruming on the backing plate, 29 fulcruming at 36 and 29-a at 36a. This combined lever action of the elements 29 and 29--a acts to spread the thrust transmitting levers I 9.

The brake shoes II and I2 are, as stated above," j;

individually shiftable to anchor at veitherend, depending upon directioi of movement of thev wheel when the brakes are applied. Steady rests 31 and 38-are. prov-idedfor restricting movement of the shoes along the axis of the drum. 'Ihe shoe, II contacts the anchor I4 at 39 and the anchor I5 at 40. The shoe I2 contacts the anchor I.4',at 4I and the anchor I5 at 42.- The .shoes thus anchor against the ends of oblong 'anchor members 43 which are secured tothe Thin plates 45, held in position by the blots.44, help to hold the shoe webs against lateral movement. A pair of relatively heavy return springs 46 and 4'I. are tensioned between the shoes II and I2 atY opposite sides of the brake. A second pair of relatively light springs V4Ii and 49 areprovided to create a differential between the forces exerte at the opposite ends of the return springs 46 and' 41. The spring 48 is hooked at 50 to the backing plate and at 5I to the uppermost coil of spring 4s. sprirg 4s (see Figure s) is hooked at sz to the backing plate and at 53 to the lowermost coil of the spring 41. n

It is believed the'mode of operation of my improved brake will be obvious from the above vdescription. Force exerted by the pressureuid in the hydraulic cylinder I 6, or alternately by manipulation of the mechanical linkage will spread the uper ends of the levers I9. The lever shown at the right of the brake will swing in a clockwise direction exerting at 24 a downward force to push shoe I2 into the drum and exerting at 26 an upward and outward force to push shoe I I against' thedrum. At the same time the lever at the left of the brake will exert similar applying forces on ,the opposite ends of the shoes. Ifv the direction of drum rotation is forward (the direction indicated by the arrow), shoe I I will .anchor at 39 and shoe I2 will anchor at 42. If

the direction of drum rotation is reversed, shoe II will anchor at 40 and shoe I2 will anchor at 4I. In either case a balanced shoe spreading force is exerted between each pair of adjacent shoe ends by the levers I9. The anchored end of one shoe servesas a fulcrum about which the associated lever I9 moves to apply the unanchored end of the other shoe. The light springs 48 and 49 serve to improve or speed up braking during forward rotation of the drum.

Since the spring 48 is hooked to the backing plate and to the upper coil of spring 46, the force of spring 48 will tend to hold the left end ofthe shoe II away from the drum luntil the left end of the shoe I2 has been moved against-the' drum. This is true because the force of the spring 43 tends to hold thev shoe II against its anchor at 39 but has no' effect on the movement of the shoe I2. Consequentlyl the lever AI9 will tend to pivot on shoe II andto apply shoe I2. The same effect is secured at the other side of the brake by the springs" and 49, except that in this'case spring 49 tends to hold the right end of the shoe I2 against its anchor. Thus the right end of the shoe II is allowed to move against the drum before the right end of the shoe I2.

It therefore appears that, when the` drum is rotating in a forward direction, brake applying movement will tend to move the toe or unan- .chored portions of the respective shoes against the drum before the heel or anchored portions of the shoes are so moved. Braking when the vehicleis moving forward is therefore speeded up and made more eiective. Any accompanying loss in the Vspeed or eifectiveness of braking during rearward motion is not, under ordinary driving conditions, as important as the advantage gained for braking during forward motion.

The modification shown in Figures 5 and 6 is substantially the same as the brake already described. However, the anchors each comprise a solid block 60, which is held to the backing plate by a pair of bolts 6I. Flanges 62 on the anchor serve to hold the webs of the shoes against lateral movement. Each of t-he levers I9 is pivotally secured to one end of the web of shoel II 2;) by means of a pin 63. A thrust link 64 is fixed at 65 to the lower eri-d of each lever I9 and at 66 to the opposite upper end of the shoe I2. There- `fore, thrust applied by the hydraulic cylinder to the levers I9 swings the levers about the point 5 53 to exert a thrust through the links 64 on the ,.--fre/s'p'ective ends of the shoe I 2. At the same time .the resistance of the ends of shoe I2 against brake applying movement tends to cause the levers lI9 to fulcrum about the point 65 andto 3U thus carry the respective ends of the shoe II toward the brake drum.

The modification of Figures 7 and 8 is similar to the brake shown in Figure 1 except that the lower end of the lever I9 does not rcontact the end of tne shoe I2, but instead contacts the upper end of a thrust link 10. As shown in Figure 8 the thrust link 'I9 is notched at 1I to receive the lower end of the lever I9 and is notched at I2 to receive the upper end of the shoe4 I2..

40 'Ihe operation of this modication' is in all respects similar to the brake of Figure 1 except of course that the thrust downward on the shoe I2 is applied through the link 10. In either of the modications of my improved brake, the two brake shoes are so designed as to be interchangeable. In this respect the modications may have some commercial advantage over the brake of Figure 1. g l

It will be understood that in the modiiications shown the brake is in each case symmetrically arranged in the manner of the brake of Figure l.

Whilev I have shown-several embodiments of my invention, it is intended thatthe showing and description be merely illustrative. It is therefore my intention not to limit my invention otherwise lthan by the terms of the appended claims.

I claim: 1. A brake comprising a pair of shoes arranged C0 to anchor individually at opposite ends in forward and reverse braking, a wheel-cylinder hydraulic applying device, and two balanced-thrust mechanical devices operated by the hydraulic applying device and each ofwhich acts with balancedA thrusts on the ends of the shoes at one side of the.brake, the hydraulic device being i'lxedly mounted and the mechanical devices each comprising a lever having its body portion on one side of the web of one of the shoes and having a portion folded over the: web to hold the said lever in alignment with the shoe and to provide a pivot for the lever on the shoe'web.

2. A brake comprising 'a pair of shoes arranged Yto anchor individually at opposite ends in forward and reverse braking, a wheel-cylinder hydraulic applying devicel having apair of pistons, and two balanced-thrust mechanical devices operated by the hydraulic applying device and each w of which acts with balanced thrusts on lthe ends of the shoes at one side of `the brake, each mechanical device consisting of a lever pivotally mounted on one shoe and linked to the other shce and a link connected to the lever and contacting one of the pistons.

3. A brake comprising a pair of shoes arranged to anchor individually at opposite ends in forward and reverse braking, a pair of op- Cil positely disposed anchors, a wheel-cylinder hydraulic applying device', and two balanced-thrust mechanical devices operated vby the hydraulic applying device and each of which. acts with balanced thrusts on the ends of the shoes 'at one side of the brake, each mechanical device consisting of a lever pivotally mounted -en one shoe and having thrust engagement with the end of the other shoe, bcth the pivot point of the lever andthe thrust engagement point of the lever being on the same side of a center line extending through the brake from anchor to anchor. 4

4. A brake comprising a pair of shoes arranged to anchor individually at opposite ends in forward and reverse braking, a wheel-cylinder hydraulic applying device, and two balanced-thrust mechanical devices operated by the hydraulic applying device and each of which acts with balanced thrusts on the ends of the shoes at one.

side of the brake, together with a mechanical emergency applying'device acting on the ends of the shoes at one side of the brake independently of the hydraulic device.

5. A brake comprising a pair of shoes arranged to anchor individually at opposite ends in forward andreverse braking, a wheel-cylinder hydraulic applying device, and two balanced-thrust mechanical devices operated by the hydraulic applying device and each of which acts with balanced thrusts on the ends of the shoes at one applying device and each lof which acts with balanced thrusts on the ends of the shoes at one'side of the brake, each mechanical device comprising -a lever adapted to contact one shoe atone point and the other shoe at another point, all of the said contact points of both levers against'both shoes being on the same side of the center of the brake.

7. A brake comprising a pair of shoes arranged to anchor individuallyfat opposite ends in forward and reverse braking--one of said shoes hav- 'ing projections at each end extending toward the other shoe, a wheel cylinder hydraulic applying device, and two balanced thrust mechanical devices operated by the hydraulic applying device, each of the mechanical devices consisting of levers h'aving a partv engaging the aforesaid projections on oneof the shces and a part A:folded over the webof the other of the shoes.

8. A brake comprising a pair of shoes arranged -to anchor individually at opposite ends in forward and reverse braking-one of said shoes' having projections at each end extending toward the other shoe, a wheel cylinder hydraulic applying device, mechanical linkage operating independently ofthe hydraulic device, and two balanced thrust mechanical devices operable by the hydraulicapplying device or the mechanical linkage, each of the mechanical devices 4consisting of levers having a part engaging the aforesaid projections on' one of the shoes and a part folded over the web of the other of the shoes. 

